Security products and/or products of value, such as identity documents, access control cards, motor vehicle documents, bills, postage stamps, revenue stamps, visas, tickets, or bank cards typically comprise defined security features which are to make it difficult or even impossible to forge them. Security features that can be detected by humans can be divided into optical, haptic, and acoustic security features. The security and/or value documents according to the invention described in more detail below comprise an optical security element.
DE 10 2009 038 904 A1 describes products of value or security products with an electroluminescent security element that is designed as an organic light-emitting diode (OLED). The OLED described there is encapsulated in a special sandwich structure to protect it from environmental influences. OLEDs require relatively high operating voltages, however, such that either ports for an external power supply are needed or adequately dimensioned energy storage devices for supplying the operating voltage must be integrated into the security product or product of value. It should further be noted that known OLEDs are operated with direct voltage, which would require a rectifier if power supply is passive. Furthermore, OLED devices are sensitive to mechanical stresses, which limits their use in products of value and security products, especially on bills, postage stamps, and tickets. Mechanical stresses may for example cause micro cracks in the encapsulation, and since the active elements of the OLED, especially the electrode, do not have any other protective layers, penetrating water and oxygen can then reduce or completely destroy the functionality of the component. And finally, operating conventional OLEDs requires a relatively high work function, which is one of the factors determining the material selection for the electrodes.
It would therefore be advantageous to provide a security product or product of value which overcomes or at least reduces the disadvantages of prior art mentioned above.